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new MK3s kit assembled but hotbed issues  

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pwiltsey
(@pwiltsey)
New Member
new MK3s kit assembled but hotbed issues

New kit assembled this past weekend, but cannot pass wizard config.  Have tried reconnecting the thermistor cable, but the thermistor is on part of the bed that does not seem to heat-up much, so not sure if thermistor problem or bed problem.

Initial Wizard Error ( calibration ) error

 

Initial temps at power-on ( assuming thermistors are correct )

 

Visual inspection, but not sure what to look for

 

Cable connections re-checked and verified

 

Manually set bed to 40 deg C to test

 

after 30 seconds of heating ... not much change for bed, tried for 5 mins and did get to 33 deg for bed ( according to thermistor )

 

Actual hotbed temp using infrared thermometer in deg C .. after 30 seconds heating

 

What do we suspect I need to check or replace ?

Best Answer by lee.g:

I am certain you are correct with your diagnosis.

The heat bed is made up of different circuits and difference in temps that you show tally perfectly with the different circuits on the bed. 

Posted : 20/05/2020 5:27 pm
pwiltsey
(@pwiltsey)
New Member
Topic starter answered:
RE: new MK3s kit assembled but hotbed issues

I am also wondering if I should start testing the thermistor per: https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-hardware-firmware-and-software-help/self-test-error-heater-thermistor-not-connected/ or if that is pre-mature and I should do something more basic first?

Posted : 20/05/2020 7:12 pm
pwiltsey
(@pwiltsey)
New Member
Topic starter answered:
RE: new MK3s kit assembled but hotbed issues

Confirmed thermistor function with a an ohm-meter and a hair drier 🙂

Reseated plugs ... still failed.

manually heated bed again ... outsided of bed were 89 - 90 degrees, middle was 29-31 .. failed

reran wizard a final time, with a hair drier heating the middle of bed ... passed successfully.

 

I think all this pointing to a faulty bed.  Any additional guidance?

Posted : 20/05/2020 11:11 pm
lee.g
(@lee-g)
Estimable Member
RE: new MK3s kit assembled but hotbed issues

I am certain you are correct with your diagnosis.

The heat bed is made up of different circuits and difference in temps that you show tally perfectly with the different circuits on the bed. 

...
Posted : 21/05/2020 11:21 am
pwiltsey
(@pwiltsey)
New Member
Topic starter answered:
RE: new MK3s kit assembled but hotbed issues

So thanks to an awesome troubleshooting session with support ( I learned a lot ), the bed was confirmed to be an issue and I received the RMA replacement this morning.  All checks and calibrations passed immediately after installation, and after a brief "Live Z" adjustment, I am off and printing within 30 mins of power-up.  Thanks Prusa and community.

Posted : 30/05/2020 2:48 am
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